/* tinyproxy - A fast light-weight HTTP proxy
 * Copyright (C) 2002, 2004 Robert James Kaes <rjkaes@users.sourceforge.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/* The functions found here are used for communicating across a
 * network.  They include both safe reading and writing (which are
 * the basic building blocks) along with two functions for
 * easily reading a line of text from the network, and a function
 * to write an arbitrary amount of data to the network.
 */

#include "main.h"

#include "heap.h"
#include "network.h"

/*
 * Write the buffer to the socket. If an EINTR occurs, pick up and try
 * again. Keep sending until the buffer has been sent.
 */
ssize_t safe_write(int fd, const char *buffer, size_t count) {
	ssize_t len;
	size_t bytestosend;

	assert(fd >= 0);
	assert(buffer != NULL);
	assert(count > 0);

	bytestosend = count;

	while (1) {
		len = send(fd, buffer, bytestosend, MSG_NOSIGNAL);

		if (len < 0) {
			if (errno == EINTR)
				continue;
			else
				return -errno;
		}

		if ((size_t) len == bytestosend)
			break;

		buffer += len;
		bytestosend -= len;
	}

	return count;
}

/*
 * Matched pair for safe_write(). If an EINTR occurs, pick up and try
 * again.
 */
ssize_t safe_read(int fd, char *buffer, size_t count) {
	ssize_t len;

	do {
		len = read(fd, buffer, count);
	} while (len < 0 && errno == EINTR);

	return len;
}

/*
 * Send a "message" to the file descriptor provided. This handles the
 * differences between the various implementations of vsnprintf. This code
 * was basically stolen from the snprintf() man page of Debian Linux
 * (although I did fix a memory leak. :)
 */
int write_message(int fd, const char *fmt, ...) {
	ssize_t n;
	size_t size = (1024 * 8); /* start with 8 KB and go from there */
	char *buf, *tmpbuf;
	va_list ap;

	if ((buf = (char *) safemalloc(size)) == NULL)
		return -1;

	while (1) {
		va_start(ap, fmt);
		n = vsnprintf(buf, size, fmt, ap);
		va_end(ap);

		/* If that worked, break out so we can send the buffer */
		if (n > -1 && (size_t) n < size)
			break;

		/* Else, try again with more space */
		if (n > -1)
			/* precisely what is needed (glibc2.1) */
			size = n + 1;
		else
			/* twice the old size (glibc2.0) */
			size *= 2;

		if ((tmpbuf = (char *) saferealloc(buf, size)) == NULL) {
			safefree(buf);
			return -1;
		} else
			buf = tmpbuf;
	}

	if (safe_write(fd, buf, n) < 0) {
		safefree(buf);
		return -1;
	}

	safefree(buf);
	return 0;
}

/*
 * Read in a "line" from the socket. It might take a few loops through
 * the read sequence. The full string is allocate off the heap and stored
 * at the whole_buffer pointer. The caller needs to free the memory when
 * it is no longer in use. The returned line is NULL terminated.
 *
 * Returns the length of the buffer on success (not including the NULL
 * termination), 0 if the socket was closed, and -1 on all other errors.
 */
#define SEGMENT_LEN (512)
#define MAXIMUM_BUFFER_LENGTH (128 * 1024)
ssize_t readline(int fd, char **whole_buffer) {
	ssize_t whole_buffer_len;
	char buffer[SEGMENT_LEN];
	char *ptr;

	ssize_t ret;
	ssize_t diff;

	struct read_lines_s {
		char *data;
		size_t len;
		struct read_lines_s *next;
	};
	struct read_lines_s *first_line, *line_ptr;

	first_line = (struct read_lines_s *) safecalloc(sizeof(struct read_lines_s), 1);
	if (!first_line)
		return -ENOMEM;

	line_ptr = first_line;

	whole_buffer_len = 0;
	for (;;) {
		ret = recv(fd, buffer, SEGMENT_LEN, MSG_PEEK);
		if (ret <= 0)
			goto CLEANUP;

		ptr = (char *) memchr(buffer, '\n', ret);
		if (ptr)
			diff = ptr - buffer + 1;
		else
			diff = ret;

		whole_buffer_len += diff;

		/*
		 * Don't allow the buffer to grow without bound. If we
		 * get to more than MAXIMUM_BUFFER_LENGTH close.
		 */
		if (whole_buffer_len > MAXIMUM_BUFFER_LENGTH) {
			ret = -ERANGE;
			goto CLEANUP;
		}

		line_ptr->data = (char *) safemalloc(diff);
		if (!line_ptr->data) {
			ret = -ENOMEM;
			goto CLEANUP;
		}

		ret = recv(fd, line_ptr->data, diff, 0);
		if (ret == -1) {
			goto CLEANUP;
		}

		line_ptr->len = diff;

		if (ptr) {
			line_ptr->next = NULL;
			break;
		}

		line_ptr->next = (struct read_lines_s *) safecalloc(sizeof(struct read_lines_s), 1);
		if (!line_ptr->next) {
			ret = -ENOMEM;
			goto CLEANUP;
		}
		line_ptr = line_ptr->next;
	}

	*whole_buffer = (char *) safemalloc(whole_buffer_len + 1);
	if (!*whole_buffer) {
		ret = -ENOMEM;
		goto CLEANUP;
	}

	*(*whole_buffer + whole_buffer_len) = '\0';

	whole_buffer_len = 0;
	line_ptr = first_line;
	while (line_ptr) {
		memcpy(*whole_buffer + whole_buffer_len, line_ptr->data, line_ptr->len);
		whole_buffer_len += line_ptr->len;

		line_ptr = line_ptr->next;
	}

	ret = whole_buffer_len;

	CLEANUP: do {
		line_ptr = first_line->next;
		if (first_line->data)
			safefree(first_line->data);
		safefree(first_line);
		first_line = line_ptr;
	} while (first_line);

	return ret;
}

/*
 * Convert the network address into either a dotted-decimal or an IPv6
 * hex string.
 */
char *
get_ip_string(struct sockaddr *sa, char *buf, size_t buflen) {
	assert(sa != NULL);
	assert(buf != NULL);
	assert(buflen != 0);
	buf[0] = '\0'; /* start with an empty string */

	switch (sa->sa_family) {
	case AF_INET: {
		struct sockaddr_in *sa_in = (struct sockaddr_in *) sa;

		inet_ntop(AF_INET, &sa_in->sin_addr, buf, buflen);
		break;
	}
	case AF_INET6: {
		struct sockaddr_in6 *sa_in6 = (struct sockaddr_in6 *) sa;

		inet_ntop(AF_INET6, &sa_in6->sin6_addr, buf, buflen);
		break;
	}
	default:
		/* no valid family */
		return NULL;
	}

	return buf;
}

/*
 * Convert a numeric character string into an IPv6 network address
 * (in binary form.)  The function works just like inet_pton(), but it
 * will accept both IPv4 and IPv6 numeric addresses.
 *
 * Returns the same as inet_pton().
 */
int full_inet_pton(const char *ip, void *dst) {
	char buf[24], tmp[24]; /* IPv4->IPv6 = ::FFFF:xxx.xxx.xxx.xxx\0 */
	int n;

	assert(ip != NULL && strlen(ip) != 0);
	assert(dst != NULL);

	/*
	 * Check if the string is an IPv4 numeric address.  We use the
	 * older inet_aton() call since it handles more IPv4 numeric
	 * address formats.
	 */
	n = inet_aton(ip, (struct in_addr *) dst);
	if (n == 0) {
		/*
		 * Simple case: "ip" wasn't an IPv4 numeric address, so
		 * try doing the conversion as an IPv6 address.  This
		 * will either succeed or fail, but we can't do any
		 * more processing anyway.
		 */
		return inet_pton(AF_INET6, ip, dst);
	}

	/*
	 * "ip" was an IPv4 address, so we need to convert it to
	 * an IPv4-mapped IPv6 address and do the conversion
	 * again to get the IPv6 network structure.
	 *
	 * We convert the IPv4 binary address back into the
	 * standard dotted-decimal format using inet_ntop()
	 * so we can be sure that inet_pton will accept the
	 * full string.
	 */
	snprintf(buf, sizeof(buf), "::ffff:%s", inet_ntop(AF_INET, dst, tmp, sizeof(tmp)));
	return inet_pton(AF_INET6, buf, dst);
}
